1. Field of the Invention
In the art of cleaning compositions for use in cleaning hard surfaces, particularly the art of cleaning tableware and other food-soiled utensils in machine dishwashers, the problem of spotting, filming and defoaming of the machine washload is present. Liquid detergent compositions were introduced to the market and offered ease and convenience of handling. Since their introduction, such detergent compositions have captured upwards of 30 percent of the home market. However, these liquid detergent compositions have suffered certain deficiencies relative to powdered machine dishwashing detergents. Specifically, although they offer ease of manufacture and handling, they have inferior spotting, filming and defoaming characteristics relative to the powdered compositions.
It is believed that these deficiencies are the result of the fact that most detergent compositions contain a chlorine bleach component, such as hypochlorite bleach, and these chlorinating agents degrade conventional defoaming nonionic surfactants such as ethylene oxide/propylene oxide block copolymers and fatty alcohol, fatty acid, fatty amide and alkyl phenol oxyalkylates. As the chlorinating agent attacks the nonionic surfactant, the bleach is depleted and the surfactant is destroyed. Thus, desirable, low spotting, filming and defoaming properties are lost along with the properties of the chlorinating agent.
In the past, liquid automatic dishwashing detergent compositions have been formulated with anionic surfactants such as alkyl diphenyloxide disulfonates, or with no surfactants present at all. The use of anionic surfactants or no surfactants in liquid automatic dishwashing detergent compositions contributes greatly to the spotting, filming and defoaming problems associated with such liquid compositions. Thus, there is a greatly felt need in the industry to formulate a liquid, automatic dishwashing detergent composition which contains nonionic surfactants and which do not break down under attack from chlorinating agents which may be present in the composition.
The present invention relates to the use of alkyl and/or aryl silyl ether capped polyethers as nonionic surfactants in liquid or slurry cleaning formulations which include alkaline hypochlorite bleaching agents. The use of these silyl capped polyethers allows such formulations to retain their cleaning and defoaming properties for longer periods than formulations containing conventional nonionic polyether surfactants.
2. Description of the Related Art
Heckert et al, U.S. Pat. No. 4,005,030 disclosed that the detergent composition containing an anionic detergent and a organosilane is capable of imparting soil release benefits to hard surfaces which are washed therein. The organosilane component of Heckert et al has the formula: ##STR1## or is a siloxane oligomer thereof wherein R.sub.1 is an alkyl group containing 1 to 4 carbon atoms or EQU Z(OC.sub.x H.sub.2x).sub.m
where x is 2 to 4, m is 1 to 20, and Z is hydrogen, an alkyl group containing 1 to 3 carbons, or an acyl group containing 1 to 4 carbon atoms; R.sub.2 is an alkyl group containing 1 to 12 carbon atoms; a is 0 to 2; R.sub.3 is hydrogen or an alkyl group containing 1 to 12 carbon atoms; b is 1 to 3; c is 0 or 1; R.sub.4 is an alkyl, aryl or aryl alkyl group containing 1 to 12 carbon atoms, a carboxy-substituted alkyl group containing 1 to 4 carbon atoms, EQU (C.sub.x H.sub.2x O).sub.m Z
where x, m and Z are as defined above, or oxygen provided only one R.sub.4 is oxygen; R.sub.5 is an alkyl, aryl or arylalkyl group containing 1 to 12 carbon atoms; X is halide; and Y is nitrogen, sulfur, or phosphorus and the sum of the carbon atoms in R.sub.2, R.sub.3, and R.sub.5 and R.sub.4 when R.sub.4 is alkyl, aryl, arylalkyl or carboxy-substituted alkyl does not exceed 20 carbon atoms. The present invention is not concerned with siloxanes or polysiloxanes but rather with compositions containing silyl groups. Accordingly the present invention differs from Heckert et al.
Wegst et al, U.S. Pat. No. 3,829,386 disclose an emulsion of a silicone-based foam depressant which is dispersed in low cloud point liquid nonionic surfactants. The surfactants are stable over a wide temperature and concentration range and can be easily incorporated into solid alkaline dishwashing and detergent compositions. There is no mention in Wegst et al of the capping of which is useful in the present invention. Further, it is not contemplated to use the surfactant from dispersant emulsions of Wegst in a liquid detergent composition. There is no recognition of chlorine stability and accordingly the present invention differs from Wegst et al.
Van der Loo et al, U.S. Pat. No. 3,994,818 disclose detergent compositions comprising:
(a) a C.sub.8 to C.sub.18 alcohol ethoxylate which contains from 2 to 4 moles of ethylene oxide per mole of alcohol, PA1 (b) a C.sub.7 to C.sub.13 alcohol or mixture thereof, PA1 (c) a C.sub.1 to C.sub.8 alcohol or C.sub.8 to C.sub.18 alcohol ethoxylate containing from 5 to 9 moles of ethylene oxide per mole of alcohol.
As a defoamer, a polyalkylsiloxane such as polydimethylsiloxane is added. The present invention is not concerned with the use of polysiloxanes, but rather is concerned with the use of silyl groups as capping agents to enhance the chlorine stability of nonionic surface active agents. Accordingly, the present invention differs from Van der Loo et al.
Kinstedt, U.S. Pat. No. 4,005,025 discloses aqueous anionic detergent compositions and containing an organosilane which imparts soil release benefits to hard surfaces washed therewith. The silicone compound of Kinstedt is an organic salt containing quaternary ammonium sulfur or phosphorus moieties. There is no mention of the stable silyl group capped polyethers as surfactants in the liquid cleaning detergents and no understanding of the chlorine bleach stable properties of the silyl capped polyethers of the present invention.